Chocolate Chip Cookie Cake

Ingredients

• 1 large egg
• 1/4 cup granulated sugar
• 1 teaspoon baking soda
• 2 cups powdered sugar
• 1/2 teaspoon vanilla extract
• 2 1/4 cups all-purpose flour
• 1/4 cup cornstarch
• 1 1/2 teaspoons vanilla extract
• 3/4 teaspoon kosher salt
• 1 large egg yolk
• pinch of kosher salt
• 3/4 cup light brown sugar (loosely packed)
• 1/2 cup unsalted butter, (softened)
• 3/4 cups unsalted butter, (softened)
• 12 ounces chocolate chips ((semi-sweet or bittersweet))
• 1 to 2 tablespoons heavy cream
• rainbow sprinkles (for garnish)